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参数资料
| 型号： | LM4667 |
| 厂商： | National Semiconductor Corporation |
| 元件分类： | 音频放大器 |
| 英文描述： | Filterless High Efficiency 1.3W Switching Audio Amplifier |
| 中文描述： | 滤波高效率的1.3W开关音频放大器 |
| 文件页数： | 4/16页 |
| 文件大小： | 757K |
| 代理商： | LM4667 |
Application Information (Continued)
REFERENCE DESIGN BOARD SCHEMATIC
In addition to the minimal parts required for the application
circuit, a measurement filter is provided on the evaluation
circuit board so that conventional audio measurements can
be conveniently made without additional equipment. This is a
balanced input / grounded differential output low pass filter
with a 3dB frequency of approximately 35kHz and an on
board termination resistor of 300
(see schematic). Note
that the capacitive load elements are returned to ground.
This is not optimal for common mode rejection purposes, but
due to the independent pulse format at each output there is
a significant amount of high frequency common mode com-
ponent on the outputs. The grounded capacitive filter ele-
ments attenuate this component at the board to reduce the
high frequency CMRR requirement placed on the analysis
instruments.
Even with the grounded filter the audio signal is still differ-
ential, necessitating a differential input on any analysis in-
strument connected to it. Most lab instruments that feature
BNC connectors on their inputs are NOT differential re-
sponding because the ring of the BNC is usually grounded.
The commonly used Audio Precision analyzer is differential,
but its ability to accurately reject fast pulses of 160nS width
is questionable necessitating the on board measurement
filter. When in doubt or when the signal needs to be single-
ended, use an audio signal transformer to convert the differ-
ential output to a single ended output. Depending on the
audio transformer’s characteristics, there may be some at-
tenuation of the audio signal which needs to be taken into
account for correct measurement of performance.
Measurements made at the output of the measurement filter
suffer attenuation relative to the primary, unfiltered outputs
even at audio frequencies. This is due to the resistance of
the inductors interacting with the termination resistor (300
)
and is typically about -0.35dB (4%). In other words, the
voltage levels (and corresponding power levels) indicated
through the measurement filter are slightly lower than those
that actually occur at the load placed on the unfiltered out-
puts. This small loss in the filter for measurement gives a
lower output power reading than what is really occurring on
the unfiltered outputs and its load.
200405C7
FIGURE 4.
LM4667
www.national.com
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相关代理商/技术参数 |
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| LM4667ITL | 制造商:Texas Instruments 功能描述:Audio Amp Speaker 1-CH Mono 1.3W Class-AB 9-Pin uSMD T/R 制造商:Texas Instruments 功能描述:1.3W Switching Audio Amplifier,LM4667ITL |
| LM4667ITL/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| LM4667ITLX | 制造商:Texas Instruments 功能描述:Audio Amp Speaker 1-CH Mono 1.3W Class-AB 9-Pin uSMD T/R |
| LM4667ITLX/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| LM4667MM | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
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